As part of the temple endowment ceremony each Mormon receives a new name which they are instructed that they "should always remember and which (they) must keep sacred and never reveal, except at a certain place..." (footage)

Since January 1, 1965 each Mormon who goes through the temple on any given day receives the exact same new name, regardless of which temple they attend across the globe. Since December, 2013 a separate new name has been given to patrons receiving their own living endowment to distinguish them from ordinances performed by proxy for the dead.

These names are told to the temple workers each day during a special prayer meeting. Every temple has a set of placards with male and female names on them, in addition to a small number. The number is the day of the month. The choice of which new name a temple patron receives depends only on their gender, whether the ordinance is live or proxy, and the day of the month.

The only confirmed exception to this rule occurs when the new name of the day coincides with the person's actual first given name, in which case he/she receives the replacement name of Adam/Eve respectively. This has been known to occur even in cases of near matches, such as Paul/Saul. For endowments given in languages other than English, new names are translated to their nearest equivalent in that language.

This website is a collection of new name submissions and information that has been inferred from them.

In a meeting with the workers in the Saint George temple, John D. T. McAllister of the temple presidency said "With regard to new Names, give easy names to be understood: Scripture names or names not in the Scripture, there are many good names of those who have lived upon the earth which are easy to understand[;] don't give any fanciful names, [and] be Sure they get the New Name and that they understand it." (Minutes, Meeting of Workers in St. George Temple, August 31, 1880, typed excerpt, Buerger Papers)

In 1970 a letter was sent from the First Presidency to all temple presidents regarding procedures in transmitting a patron's new name, which included the following text:
"Because of its sacred and confidential nature, this information should not be transmitted by mail or by telephone; therefore, the First Presidency recommends that you use a simple code system which will be made known to each temple president who will keep it in a special file. The information requested may then be transmitted by letter or if necessary by telephone using combinations of numbers. The information will be given only by a temple president to another temple president - never to the patron directly.Of course, the need for this applies only to those sisters who were endowed prior to January 1, 1965, when the present new name system was adopted.
The method is this: Instead of spelling out the new name, the numbers corresponding to the letters in the new name should be transmitted along with a person's name and date of the endowment.
example:
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26
If the name given were Martha, the numbers transmitted would be: "The information you seek on behalf of ________ is 13-1-18-20-8-1."
We ask that after January 1, 1971, all temple presidents use the simple code system herein outlined when transmitting the new name on behalf of patrons who need such information."(Joseph Fielding Smith, Harold B. Lee, and N. Eldon Tanner to temple presidents, Dec. 21, 1970, copy in Buerger Papers, quoted in Development of LDS Temple Worship, Anderson, p 389)

We have received 30 submissions of new names given prior to 1965, and consistent with this information no coherent pattern has yet been identified.

Ca. 1844 to October 24, 1878

Female Name

Male Name

Sarah

Abraham

In 1846, a writer calling herself "Emeline" wrote to the Warsaw Signal that sometime in the previous two years she had received her endowment at Nauvoo, and while her new name was redacted by the editor of the paper, she wrote that "from all that I can gather, all the females had the same name given them, but we are not allowed to reveal it to each other." (Communications, Warsaw Signal, April 15, 1846, Vol 3, No 3)

Fanny Stenhouse wrote that in 1860 "A new name was then whispered into my ear, which I was told I must never mention to any living soul except my husband in the Endowment House... There was among our number a deaf woman; Mrs. Whitney had to tell her her name once or twice over, loud enough for me to hear, and thus I found that her new name, as well as mine, was Sarah. To make the matter worse, another sister whispered: 'Why that is my name too.' This entirely dispelled any enthusiasm which otherwise I might have felt. I could well understand that I might yet become a Sarah in Israel, but if we all were Sarahs, there would not be much distinction or honor in being called by that name. As a matter of course I supposed that the men would all become Abrahams." (Tell It All, The Story of a Life's Experience in Mormonism, pgs 360-361)

Ann Eliza Young, wife of Brigham Young, reported that in 1860 or 1861 she received her new name, and wrote "If the Mormon doctrine were true, there would be a mighty shouting for 'Sarah' at that time, as every person whose name I have heard was always called the same. It was the name that was given me, and I have known many others who received it." (Wife Number 19, pg 361)

Hans P. Freece wrote to his son, "Yes, I have been in the Endowment House more than once. In 1865 my first wife and I, with others of the faithful, went through ...we had received new names, and we had lost our identities. My new name was a secret until I heard some one yell into the ear of a deaf brother, 'Your new name is Abraham.' I gave a sudden start, for I thought that name was for me alone. Forty years have rolled by, and every man with whom I have had conversation has told me that his name was Abraham." (The Letters of an Apostate Mormon to his son, 1908)

Caroline Owens Miles discussed her endowment and marriage, which occurred on October 24, 1878, saying that the woman who performed her washings and anointings "whispered my new and celestial name in my ear. I believe I am to be called up on the morning of the resurrection by it. It was Sarah. I felt disappointed. I thought I should have received a more distinguished name. She told me that my name must never be spoken, but often thought of, to keep away evil spirits. I should be required to speak it once that day, but she would tell me in what part of the ceremony, and that I should never again have to speak it."(The Boston Daily Globe, Monday, April 18, 1881)

From the above, it appears that the new name originated with the story of Abram and Sarai in the Old Testament, who received the new names Abraham and Sarah respectively, and that everyone until at least October 24, 1878, received these two names regardless of the day of the month.